Modern telephone exchanges are generally controlled by an electronic processor which is designed to monitor connections between subscribers and to control a plurality of peripheral units required for the operation of the exchange.
In a telephone exchange, it is necessary to process data words having different length or format such as an address comprising 16 bits call-number digit comprising four bits.
Computers include a data memory having predetermined memory zones each of which is adapted to store one word.
If a 16-bit word is chosen, each zone of the data memory will then have as many cells as there are bits, i.e. 16, to be stored
Conventional processors have the disadvantage that when the length of the data words to be processed is widely variable, the efficiency of the data memory is very poor since a zone 16 bits long is engaged, for example, to store a 4-bit call-number digit.
In the example described above, only one fourth of the storage capacity of a given memory zone designed to accommodate four digits is utilized.
A processor capable of handling a given amount of traffic, whose data memory is used with such a poor efficiency, must therefore include a number of memory modules which is three and sometimes four times the number of memory modules in a processor in which advantage is taken of its full potential storing capacity.
Thus, full utilization of the data memory makes it possible to reduce to one third or one fourth the number of memory modules, which results in substantial reduction in the total cost of the processor in question.